The late Princess Diana's former bodyguard advised her "strongly" not to give up her security following her divorce from the Prince of Wales, and he believes if she had of listened to him she would still be alive.
The royal tragically died in a car accident in France in 1997 aged 36, which came one year after she split from Prince Charles, but Metropolitan Police protection officer Ken Wharfe urged her not to ditch him and his team just because the couple had ended their romance.
Speaking in an upcoming two-hour programme 'The Life and Death of Princess Diana: A Dateline Investigation', which is set to air on NBC on Friday, he recalled saying to her: "Whatever you want to do, you will always be Diana, the Princess of Wales. The one thing that you shouldn't give up is your security. I urge you strongly not to do that."
Although Diana didn't take Ken's tips, he believes no one else could have convinced her to change her mind other than Queen Elizabeth II, and he thinks if she had of listened the nation's sweetheart - who has sons Prince William and Prince Harry - would still be alive.
He added: "There's only one person that could - in my view - that could have insisted that she retain her security, and that would have been the queen herself.
"If the queen had insisted that she retain that security then we wouldn't be having this discussion because Diana, in my view, would have been alive today."
And Ken has claimed Diana's "big fear" was that Charles' current partner the Duchess of Cornwall would try to be her children's "substitute mother".
Ken said: "Her big fear was that this is not a substitute mother for the boys. That they would try to sideline Diana and that Camilla might use her post."